Use of the Internet by the general public is gaining popularity. More and more people are getting access to the Internet and the vast amount of information that it provides. Along with the rapid increase in the number of Internet users, advertising on the Internet has consequently become an important priority for many advertisers.
As a result, for web portals and ISPs, a significant amount of revenue can be generated from displaying advertisers' ad banners or other types of ads on displayed websites or web pages. For example, for a preeminent portal such as Yahoo! which is visited daily by millions of users, considerable revenue can be made by displaying an advertiser's ad impressions on its websites or web pages.